I am a writer.
I also have ADD.
But I suspect this experience is not entirely unfamiliar to other writers:
I’m working on a story, and then—BAM—I’m hit with a brilliant idea for another project, or a scene for later on in the piece, or a detail I want to make sure to include somewhere, etc.
I either get so absorbed in the new idea that I completely lose focus on what I was working on, or I tell myself I’ll remember the new idea (but never, ever do).
Worse still, I sometimes try to maintain focus on both at the same time, trying to remember the new idea while still working on the original piece, rendering both efforts frustratingly inaccessible and mediocre.
My hands already cramp up trying to keep up with the speed of my thoughts; now I’m trying to hold onto an idea (or more than one!) while also pursuing a separate thread of attention. It’s simply not possible.
Writing on its own is hard enough—and research reflects this.